In recent years, the European Union has introduced strict rules (Commission Regulation (EU) 2023/915) regarding the presence of toxic pyrrolizidine alkaloids (PA) in food, medicinal plants and related products.
Currently, around 600 such compounds are known, which are synthesized by around 6,000 different plants for self-defense against attacks by animals, insects and other pests. These compounds can enter the product if weeds containing PA are inadvertently collected during harvest. Even with good agricultural and harvesting practices, this possibility exists.
There is currently evidence that PA can spread in the soil and even move to neighboring plants or leach into the environment with water. PAs have also been detected in samples of herbs growing next to weeds containing toxins.
The study analyzed the behavior of PAs in soil from two weeds found in Latvia — forget-me-not (Myosotis arvensis) and groundsel (Senecio vulgaris). Two common Latvian soil types, loam and clay were selected for further investigation. The experiments used cold and hot plant extracts to determine how PAs dissolve and leach depending on the processing method and soil properties. The results show that more PAs were leached from forget-me-not extracts, especially cold extracts, because they contain more water-soluble forms of PAs. In the case of groundsel, most PAs were leached from the soil, especially in sandy substrates. However, leaching was observed to a slightly lesser extent in clay soils. On the fourteenth day, some compounds were no longer detectable.
The mobility of PAs is influenced by their chemical structure – cyclic PAs are less soluble and accumulate more on soil particles than open-chain PAs. Soil pH and moisture conditions also significantly affect the behavior of these compounds.
The study makes a significant contribution to the understanding of the risks of environmental PA pollution, which directly affects agricultural production, as well as helps to assess the potential consequences for human health.
The research is carried out within the project “Transfer of pyrrolizidine alkaloids from weeds to soil and medicinal plants (No lzp-2022/1-0543)”. The project is funded by the Fundamental and Applied Research Programme of the Latvian Council of Science
More information on the project HERE.
